A fluororesin is used for various applications in which conventional plastics cannot be used, since it is excellent in the solvent resistance, the low dielectric property, the low surface energy property, the non-adherence, the weather resistance, etc. Particularly, an ethylene/tetrafluoroethylene copolymer (hereinafter sometimes referred to as “ETFE”), which is a fluororesin excellent in the heat resistance, the flame retardancy, the chemical resistance, the weather resistance, the low abrasion property, the low dielectric property, etc., is used in a wide range of fields including a heat resistant electric wire-covering material, a corrosion resistant piping material for chemical plant, an agricultural plastic greenhouse material, a mold release film, etc. In recent years, its application to a backsheet for a solar cell attracts attention. A backsheet for a solar cell is generally required to have heat resistance, weather resistance and chemical resistance for use in a long period of time, a low dielectric property to improve the performance of the entire solar cell system, etc. Accordingly, the backsheet for a solar cell may be considered to be an application in which properties of a fluororesin represented by an ETFE can be made use of.
In order to further improve properties of a fluororesin used for various applications including a backsheet for a solar cell, for example, a technique to blend a fluororesin with other type of resins has been proposed (for example, Patent Documents 1 to 3).